InterPro domain: IPR005064

Bordetella pertussis, the causative agent of human whooping cough (pertussis), is an obligate human pathogen with diverse high-affinity transport systems for the assimilation of iron, a biometal that is essential for growth [ 1 ]. Periplasmic binding proteins of a new family, particularly well represented in this organism (and more generally in beta-proteobacteria), have been called Bug receptors [ 2 ].

They adopt a characteristic Venus flytrap fold with two globular domains bisected by a ligand-binding cleft. The family is specific for carboxylated solutes, with a characteristic mode of binding involving two highly conserved beta strand-beta turn-alpha helix motifs originating from each domain. These two motifs form hydrogen bonds with a carboxylate group of the ligand, both directly and via conserved water molecules, and have thus been termed the carboxylate pincers. Domain 1 recognises the ligand and the carboxylate group serves as an initial anchoring point. Domain 2 discriminates between productively and non-productively bound ligands as proper interactions with this domain is needed for the of the closed conformation [ 3 ].

BugE has a glutamate bound ligand. No charged residues are involved in glutamate binding by BugE, unlike what has been described for all glutamate receptors reported so far. The Bug architecture is highly conserved despite limited sequence identity [ 4 ].

1. Impact of alcaligin siderophore utilization on in vivo growth of Bordetella pertussis. Infect. Immun. 75, 5305-12
2. Crystal structure of Bordetella pertussis BugD solute receptor unveils the basis of ligand binding in a new family of periplasmic binding proteins. J. Mol. Biol. 356, 1014-26
3. Structure-based mechanism of ligand binding for periplasmic solute-binding protein of the Bug family. J. Mol. Biol. 373, 954-64
4. Structural analysis of Bordetella pertussis BugE solute receptor in a bound conformation. Acta Crystallogr. D Biol. Crystallogr. 62, 1375-81